Patent FR-1273829-A (FR)
IPC: G01S7/292
Filed: 1960-11-18
Granted: 1961-10-13
Abstract: 894,148. Pulse radar. DECCA RECORD CO. Ltd. Nov. 18, 1960 [Nov. 19, 1959], No. 39329/59. Class 40(7). Relates to a pulse radar having a range register comprising a plurality of storage elements corresponding to different range increments, the echo pulses received in any one pulse recurrence period being stored in binary form in corresponding storage elements. According to the present invention the radar comprises a directional aerial 12 rotating in azimuth, a plurality n of range registers, e.g. 20, 21, 22, where n is equal to the number of pulses radiated as the aerial sweeps through an angle equal to the aerial beam width, the echoes received during n successive recurrence periods being stored in the corresponding n range registers and means being provided for selecting from said range registers target signals within predetermined range limits R, R + #R and bearing limits #, # + ##. The selected signals may be processed to give the range and bearing of a target which may be used in an auto-alarm or auto-tracking system, the position data derived during one aerial rotation being used to set the range and bearing limits during the next aerial rotation. As described each range register 20, 21, 22 comprises a matrix of two-state storage elements and the registers are scanned by an address register 23 controlled by a clock pulse generator 24 synchronized with the pulse transmitter 10. The information from successive radar pulses is fed in sequence into the register 20 whilst any information already stored therein is simultaneously transferred to the corresponding positions in the next register 21 and so on so that the information passes to the various registers in sequence. The range gate limits R and R + #R are set up during an interscan period between two successive range information periods and are stored in range gate matrices 25, 26 respectively under the control of a range gate control circuit 27 which is operative only when the bearing of the aerial 12 is within the bearing limits # and # + ## set by a bearing limit circuit 30 as determined by a comparator 29. The output target signals from the range register system 20, 21, 22 are compared with the range limit signals from the range gate registers 25, 26 in a comparator 31 and the selected signals are correlated at 32 to discriminate against random signals, the output from the correlator 32 being applied through data processing apparatus 33 to the control circuits 27 and 30 to set the range and bearing limits during the next aerial rotation; alternatively the control circuits 27 and 30 may be set manually. In a modification (not shown) a single range gate register is used to store (1) both range limits R and R + #R or (2) the initial range limit R only; in the latter case the register is used in conjunction with a clock pulse counter which is set in operation at the commencement of each range gate to count the appropriate number of clock pulses to define the width #R of the gate. The counter may be controlled to change the gate width #R (1) manually or (2) automatically in accordance with the previously determined speed and direction of each selected target. When there are a plurality of targets located in different directions the corresponding data from the processing apparatus 33 may be stored sequentially and used to train a height-finding radar on to the various targets in sequence.